Plants and Animals

Obovaria olivaria Hickorynut

Key Characteristics

The hickorynut is a medium sized (to 4 inches) mussel with a smooth, somewhat inflated, oval or oblong shell. The shell is yellowish brown or greenish with faint rays that are visible on young individuals. The beaks are large and the beak sculpture consists of 4 to 5 subtle double-loops and is usually only visible on very young individuals. Cardinal teeth are aligned horizontally and are relatively small and triangular. The nacre is white.

Status and Rank

US Status:
State Status: E - Endangered (legally protected)
Global Rank: G4 - Apparently secure
State Rank: S1 - Critically imperiled

Occurrences

CountyNumber of OccurrencesYear Last Observed
Macomb22009
Menominee32009
Monroe31935
Ottawa71959
Saginaw12001
Washtenaw11996
Wayne82007

Information is summarized from MNFI's database of rare species and community occurrences. Data may not reflect true distribution since much of the state has not been thoroughly surveyed.

Habitat

The Hickorynut is found in large rivers and lakes in sand or sand and gravel substrates.

Specific Habitat Needs

Sandy, gravel substrates needed in: River (5th-6th order), PoolRiver (5th-6th order), Run.

Natural Community Types

  • River (5th-6th order), pool
  • River (5th-6th order), run

For each species, lists of natural communities were derived from review of the nearly 6,500 element occurrences in the MNFI database, in addition to herbarium label data for some taxa. In most cases, at least one specimen record exists for each listed natural community. For certain taxa, especially poorly collected or extirpated species of prairie and savanna habitats, natural community lists were derived from inferences from collection sites and habitat preferences in immediately adjacent states (particularly Indiana and Illinois). Natural communities are not listed for those species documented only from altered or ruderal habitats in Michigan, especially for taxa that occur in a variety of habitats outside of the state.

Natural communities are not listed in order of frequency of occurrence, but are rather derived from the full set of natural communities, organized by Ecological Group. In many cases, the general habitat descriptions should provide greater clarity and direction to the surveyor. In future versions of the Rare Species Explorer, we hope to incorporate natural community fidelity ranks for each taxon.

Management Recommendations

Like other mussels, threats to the hickorynut include: natural flow alterations, siltation, channel disturbance, point and non-point source pollution, and exotic species. Maintenance or establishment of vegetated riparian buffers can help protect mussel habitats from many of their threats. Control of zebra mussels is critical to preserving native mussels. And as with all mussels, protection of their hosts habitat is also crucial.

Active Period

Survey Methods

Aqua-scope searches

Survey Period: From first week of April to first week of October

Snorkeling searches

Survey Period: From first week of April to first week of October

SCUBA searches

Survey Period: From first week of April to first week of October

References

Survey References

  • Cummings, K.S. and C.A. Mayer. 1992. Field Guide to Freshwater Mussels of the Midwest. Illinois Natural History Survey Manual 5, Champaign. 194pp.
  • Strayer, D.L. and D.R. Smith. 2003. A Guide to Sampling Freshwater Mussel Populations. American Fisheries Society Monograph 8, Bethesda. 103pp.

Technical References

  • Badra, P.J. 2004. Special Animal Abstract for Obovaria olivaria (Hickorynut). Michigan Natural Features Inventory, Lansing, MI. 4pp.
  • Badra, P.J. and R.R. Goforth. 2002. Surveys of Native Freshwater Mussels in the Lower Reaches of Great Lakes Tributary Rivers in Michigan. Report number MNFI 2002-03. Report to Michigan Department Of Environmental Quality, Coastal Zone Management Unit, Lansing, MI. 39pp.
  • Box, J.B. and J. Mossa. 1999. Sediment, land use, and freshwater mussels: prospects and problems. Journal of the North American Benthological Society 18:99-117.
  • Cummings, K.S. and C.A. Mayer. 1992. Field Guide to Freshwater Mussels of the Midwest. Illinois Natural History Survey Manual 5, Champaign. 194pp.
  • Dillon, R.T. Jr. 2000. The Ecology of Freshwater Molluscs. Cambridge University Press, Cambridge, UK. 509pp.
  • Watters, G.T. 1993. A guide to the freshwater mussels of Ohio. Revised Edition. The Ohio Department of Natural Resources, Columbus. 106 pages.